Method for preparing homogeneous detergent slurry



United States Patent 3,355,390 METHGD FOR PREPARING HOMOGENEOUS DETERGENT SLURRY Edwin L. Behrens, Cincinnati, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Dec. 6, 1965, Ser. No. 511,985 7 Claims. (Cl. 252-137) ABSTRACT OF THE DISCLOSURE Process for preparing a homogeneous detergent slurry comprising the steps of (a) preparing an aqueous slurry comprising water, an alkylene oxide-containing nonionic synthetic detergent and the trisodium salt of nitrilotriacetic acid; and thereafter (b) adding and mixing homogenously therein sodium tripolyphosphate.

This invention pertains to a novel method for preparing a homogeneous detergent slurry comprising a nonionic synthetic detergent and an hydratable inorganic builder salt. More particularly, this invention relates to a method for preparing a smooth, readily pumpable aqueous detergent slurry which comprises mixing together in a critical proportion and in a critical sequence of steps, an alkylene oxide-containing nonionic synthetic detergent, an hydratable inorganic water-soluble alkaline builder salt, a watensoluble salt of nitrilotriacetic acid and water.

Prior to this invention, it had not been possible to incoporate an alkylene oxide-containing nonionic synthetic detergent into a detergent slurry without encountering some mixing and emulsion stability problems. Detergent slurries, or crutcher mixes as they are sometimes termed, which contain these nonionics, even in amounts as small as about 1.0% by weight of the final detergent slurry, have a tendency to resist homogenization. Such a final detergent slurry or crutcher mix is generally a viscous, heterogeneous mass. This problem is markedly accentuated by the presence in the detergent slurry of hydratable inorganic builder salts such as alkali metal pyrophosphates and polyphosphates. As these salts are added to the slurry, they appear to take up water, as water of hydration, from the slurry or induce such phase transformations that the entire slurry attains a heterogeneous, clabber-like or grainy consistency. Additionally, the slurry may separate into layers. The slurry or crutcher mix usually becomes very viscous and is unpumpable when ordinary water levels of from about 25% to about 40% are being utilized. These complex phase and stability problems have represented obstacles to attempts to heat dry, e.g., spray dry, such a detergent slurry and thereby convert it into a satisfactory granular built detergent product. This problem exists independently of the other materials present in the ordinary detergent slurries such as anionic synthetic detergents, silicates, sulfates and the like.

Accordingly, it is an object of this invention to provide a process for preparing an easily pumpable, homogeneous detergent slurry containing an alkylene oxide-containing nonionic synthetic detergent and an hydratable inorganic Water-soluble alkaline builder salt. Another object of this invention is to provide a process for preparing a homogeneous detergent slurry which can be readily employed in a spray drying operation employing typical processing conditions. It is also an object to provide such an improved process which utilizes a compound which not only solves the complex phase problems but also contributes to the overall cleaning performance of the final spray-dried granular detergent product.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.

It has now been discovered that the foregoing objects of the present invention can be obtained by a process which comprises the steps of (a) mixing, by weight of the final detergent slurry, from about 25% to about 40% water, from about 1% to about 20% of an alkylene oxide-containing nonionic synthetic detergent, and from about 1% to about 50% of a water-soluble salt of nitrilotriacetic acid, said salt of nitrilotriacetic acid being added in an amount sufficient to provide an easily pumpable, homogeneous slurry but in an amount less than its own solubility in the final slurry, and thereafter,

(b) adding and mixing homogeneously therein to form the final slurry, from about 5% to about 60% of an hydratable inorganic water-soluble alkaline builder salt, the amount of said builder salt being not more than about five times the weight of said water-soluble salt of nitrilotriacetic acid.

The essential ingredients in the process of this invention are water, alkylene oxide-containing nonionic synthetic detergents, the Water-soluble salts of nitrilotriacetic acid, and the hydratable inorganic builder salts. As mentioned above, the problem solved by the process of this invention was initially caused by mixing the specific nonionic synthetic detergents with the hydratable builder salts in an aqueous detergent slurry. It was immaterial whether the nonionic detergent was added to a mixture of Water and the hydratable builder or whether, alternatively, the hydratable builder was added to a mixture of water and the nonionic detergent. It is significant to note, however, that once the complex detergent slurry became viscous and clabber-like, it was not rendered smooth and homogeneous by subsequently adding even large amounts of water. The surprising aspect of the present invention is that the water-soluble salts of nitrilotriacetic acid, when utilized in the critical addition sequence hereinafter defined, do successfully solve this problem. The essential ingredients of the present invention will be defined at this juncture in order to facilitate a better understanding of the critical addition sequence which will be defined hereinafter.

The nonionic synthetic detergents which are utilized in the process of this invention are alkylene oxide-containing nonionic detergents. They can be broadly defined as compounds produced by the condensation of alkylene oxide (hydrophilic in nature) with an organic hydrophobic compound, which can be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between the hydrophilic and hydrophobic elements.

Suitable alkylene oxide-containing nonionic synthetic detergents of the type which are useful in this embodiment of the present invention are:

(1) The polyethylene oxide condensates of alkyl phenols and dialkyl phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing from about 6 to 12 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the said ethylene oxide being present in amounts equal to about 5 to 30 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be derived from polymerized propylene, diisobutylene, octene, or nonene, for example.

(2) Alkylene oxide-containing nonionic detergents derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine. Here again, a series of compounds are contemplated whose characteristics can be controlled by achieving a desired balance between the hydrophobic and hydrophilic elements. For example, compounds containing from about 40% to about 80% polyoxyethylene by weight and having a molecular weight of from about 5,000 to about 11,000 resulting from the reaction of ethylene oxide groups with a hydrophobic base constituted of the reaction product of ethylene diamine and excess propylene oxide, said base having a molecular weight of the order of 2,500 to 3,000, are satisfactory.

(3) The condensation product of aliphatic alcohols having from 8 to 22 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide, e.g., a coconut alcohol-ethylene oxide condensate having from about 4 to 45, preferably from 5 to 20, moles of ethylene oxide per mole of coconut alcohol. The coconut alcohol fraction which is preferred is a distilled coconut alcohol having from to 16 carbon atoms, with the approximate chain length distribution being from 2% C 66% C 23% C and 9% C Another prefered compound is the condensation product of tallow derived alcohol and from about 5 to about moles of ethylene oxide per mole of tallow alcohol; a specific illustration being the condensation reaction product of one mole of tallow alcohol and 10 moles of ethylene oxide 10)- (4) A well known class of alkylene oxide-containing nonionic synthetic detergents of this type is made available on the market under the trade name of Pluronic. These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The hydrophobic portion of the molecule which, of course, exhibits water insolubility, has a molecular weight of from about 1500 to 1800. The addition of polyoxyethylene radicals to this hydrophobic portion tends to increase the water solubility of the molecule as a whole and the liquid character of the product is retained up to the point where polyoxyethylene content is about 50% of the total weight of the condensation product. The molecular weights of Pluronic L61, L64, and F68, for example, are approximately 2000, 3000 and 8000 respectively.

Specific illustrations of the foregoing classes include the following which are merely illustrative of the type intended: nonyl phenol condensed with either about 5 or about 30 moles of ethylene oxide per mole of phenol and the condensation product of coconut alcohol with an average of either about 4 or about 15 moles of ethylene oxide per mole of alcohol and the condensation product of about 15 moles of ethylene oxide with one mole of tridecanol. Other illustrative examples are dodecylphenol condensed with 12 moles of ethylene oxide per mole of phenol; dinonylphenol condensed with 15 moles of ethylene oxide per mole of phenol; dcdecyl mercaptan condensed with 10 moles of ethylene oxide per mole of mercaptan; nonyl phenol condensed with 20 moles of ethylene oxide per mole of nonyl phenol; myristyl alcohol condensed with 10 moles of ethylene oxide per mole of myristyl alcohol; lauramide condensed with 15 moles of ethylene oxide per mole of lauramide; and diisooctylphenol condensed with 15 moles of ethylene oxide.

The water-soluble salts of nitrilotriacetic acid have the general formula CHzCOOH N-CHzCO OH CHzC O OH wherein a suitable cation is substituted for the acidic hydrogens inthe above formula, the cation being sodium;

potassium, other alkali metals, or ammonium or substituted ammonium radicals, e.g., triethanol amine. The trisodium salt of nitrilotriacetic acid (Na NTA) is the preferred water-soluble salt of nitrilotriacetic acid for use in this invention. The water-soluble salts of nitrilotriacetic acid will be referred to generally in the following description as NTA.

The hydratable water-soluble inorganic alkaline builder salts of this invention are preferably the sodium and potassium salts of tripolyphosphoric acid, that is, sodium tripolyphosphate and potassium tripolyphosphate. Other water-soluble salts of tripolyphosphoric acid can be employed such as those utilizing other alkali metals as the cation or a cation chosen from ammonium or substituted ammonium radicals. Sodium pyrophosphate and potassium pyrophosphate can also be utilized in the process of this invention. The most preferred inorganic builder salt for use in this invention is anhydrous sodium tripolyphosphate (STP).

It is contemplated that the detergent slurry of this invention can contain ordinary detergent additives as described hereinafter. It is understood, however, that these additives are not necessary to the successful practice of the invention herein described. Because these nonessential ingredients may be present, the term slurryj as hereinafter used, is defined to include water per se or water in admixture with any or all of the other additives hereinafter set forth regardless of whether those additives are dissolved in or dispersed in the water.

In order to obtain the benefits of this invention a hereinbefore outlined, the essential ingredients described above must be combined in the following critical sequence of steps.

In the first step of the process of this invention, a detergent slurry is prepared which contains water, the nonionic detergent and the NTA. Preferably, the NTA is first mixed with the detergent slurry, e.g., water, and then the nonionic detergent is added. Alternatively, the nonionic can be mixed with the detergent slurry first and then the NTA can be added to this mixture; but for reasons given below, the former sequence is highly preferred.

According to a preferred embodiment, the NTA should be added to the slurry before the alkylene oxide-containing nonionic synthetic detergent. If the nonionic is added to the slurry first, the resulting mixture tends to separate into layers, thicken and take on a grainy appearance. With the subsequent addition of NTA, however, homogeneity is again attained and viscosity is again reduced. To prevent this separation and increase in viscosity in the mixture, it is highly preferred that NTA be added to the slurry before the nonionic.

The water-soluble salts of nitrilotriacetic acid, previously described, serve the purpose of homogenizing and fiuidizing the detergent slurry and, additionally, continue to maintain the slurry in a smooth, fluid and homogeneous state throughout the subsequent addition of the nonionic detergent and especially through the critical addition of the hydratable inorganic builder salts. The addition of NTA prior to the hydratable inorganic builder salt is the essence of the process of this invention. If the hydratable builder salt is added before or along with the NTA, the slurry sets up into an unpumpable mass, i.e., it becomes grainy and clabber-like. The unpumpable condition of the slurry makes mixing virtually impossible, thereby precluding the preparation of a homogeneously blended slurry on the subsequent addition of NTA and the nonionic detergent. The addition of NTA after the hydratable builder salt does not restore the slurry to the smooth, pumpable, homogeneous slurries which are desirable and which are produced by the process of this invention, nor will the further addition of water convert the mass into a homogeneous, pumpable mixture. It has been discovered that if the NTA is first mixed with the nonionic detergent,

7 the subsequent addition of the hydratable builder salt,

e.g., STP, does not adversely affect the desired homogeneity of the slurry. The only perceptible change in the slurry is a gradual and expected increase in viscosity upon the addition of the hydratable builder salt.

In connection with this invention, it is also important to note that the NTA should not under any circumstances be added in excess of its solubility in the final detergent slurry as, at these concentrations, its effectiveness decreases rapidly. If NTA is added in excess of its solubility, the detergent slurry behaves, in some instances, as if no NTA was present at all. In all such cases, the homogenizing and fiuidizing effects of the NTA are markedly reduced,

NTA, in addition to its main function in this process of homogenizing and fiuidizing the detergent slurry, also exhibits synergistic builder action in a final heat dried, i.e., spray dried, detergent product when combined with alkaline salts of tripolyphosphon'c acid in a preferred weight ratio of NTA to the tripolyphosphoric acid salts of from about 3:1 to about 1:5. (These ratios are calculated on the basis of Na NTA and Na STP.) The synergistic builder action of NTA and the alkaline salts of tripolyphosphoric acid is more fully explained in copending patent application by Gedge, Ser. No. 498,908, filed October 11, 1965.

It was totally unexpected that an organic salt having synergistic builder capabilities, i.e., NTA, could be utilized to alleviate the processing problems attributed to another known builder such as the hydratable inorganic builder salts hereinbefore defined. Additionally, it is surprising that the order of addition of NTA to the crutcher mixture should be so important that if deviations in the sequence occur, the problem is not solved. It is also quite unexpected that the addition of NTA in excess of its solubility, but in the critical sequence herein defined, to a detergent slurry containing in its final form an alkylene oxide-containing nonionic and a hydratable iorganic builder salt will not inhibit the formation of a grainy, viscous, unpumpable slurry.

In the process of this invention, the preferred nitrilotriacetic acid salt is the trisodiurn salt (Na NTA). In a further preferred embodiment of this invention, Na NTA is utilized in the slurry in an amount, by weight of the final detergent slurry, of from about 2% to about 30%. Within this preferred range, the Na NTA is generally entirely soluble in the final detergent slurry and yet is present in such amounts as to adequately prevent the formation of the hereinbefore described heterogeneous, grainy, unpumpable slunies.

As another preferred embodiment of this process, Water comprises, by weight, from about 30% to about 38% of the final slurry. The water can be added in conjunction with nonessential ingredients, as hereinafter described, i.e., an aqueous solution of silicates, water of hydration, aqueous anionic pastes or the like, or the water can be admixed directly with the NTA or the nonionic detergent. In any event, enough water must be added to form a pumpable slurry.

According to a preferred procedure, the nonionic detergent is added to the NTA-Water slurry in amounts ranging from about 1% to about 20% by weight of the final detergent product. The preferred range for the addition of the nonionic is from about 2% to about by weight of the final detergent product.

The nonionic is added to and homogeneously mixed with the detergent slurry. Although the nonionic can be added prior to the NTA without adverse effect on the final slurry, intermediate effects are noticeable. As mentioned earlier, the nonionic-containing aqueous mixture may thicken, separate into layers, or take on a grainy appearance. Although subsequent addition of NTA will, in most cases, cause the slurry to again become homogeneous and less viscous, considerable efiiort and mixing time must be devoted to such end. It is, therefore, highly 6 preferable that the nonionic be added after the NTA has been mixed with the slurry.

After the nonionic detergent, NTA and water have been admixed into a homogeneous slurry, the hydratable builder salt is then added to the detergent slurry. The builder salt is added to and homogeneously dispersed throughout the slurry while the mixture is adequately stirred. From about 5% to about 60% of the final detergent slurry can be comprised of the hydratable inorganic builder salts hereinbefore described. The amount of the hydratable inorganic builder salt should not, however, exceed about five times the amount by weight of NTA utilized in this process. If this limit is exceeded, the slurry tends to become grainy and layered; in some instances, the slurry will become unpumpable.

The entire mixing operation of this invention can be accomplished at temperatures between about 65 F. and 200 F. It has, however, been found especially beneficial to employ temperatures from F. to F. Within this preferred temperature range, the final slurry is at a 'sufiiciently high temperature to facilitate ordinary spray drying procedures. The slurry is, however, not hot enough to subject the hydratable inorganic builder salts to hydrolytic degradation.

The resultant slurry prepared by the process taught herein is smooth and homogeneous. No layering of the various detergent ingredients can be discerned. The slurry is pumpable and suitable for spray drying. Excellent detergent granules can be obtained by spray drying this final detergent slurry.

Although not essential to the process of this invention, the detergent slurry contemplated in this invention can contain detergent substances such as soap, anionic synthetic non-soap detergents, nonionic synthetic detergents of the amine oxide and phosphine oxide type, ampholytic synthetic detergents and zwitterionic synthetic detergents, and mixtures thereof. The addition of these detergent substances forms no limitation on this invention, but is intended to be includable within the terms of claims calling for a detergent slurry comprising various detergent ingredients in accordance with the teachings herein. Ordinarily such optional ingredients are added to the slurry early in the process, preferably before or along with the NTA.

Examples of suitable soaps are the sodium, potassium and alkylolammonium salts of higher fatty acids (C C Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap.

=The other suitable detergent substances are outlined at more length as follows:

(a) Anionic synthetic non-soap detergents can be broadly described as the water-soluble salts, particularly the alkali metal salts, of organic sulfuric reaction products having in their molecular structure an alkyl radical containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. (Included in the term alkyl is the alkyl portion of higher acyl radicals.) Important examples of the synthetic detergents which form a part of the preferred compositions of the present invention are the sodium or potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (C C carbon atoms) produced by reducing the glycen'des of tallow or coconut oil; sodium or potassium alkyl benzene sulfonates, in which the alkyl group contains from about 9 to about 15 carbon atoms, including those of the types described in United States Letters Patents Numbers 2,220,- 099 and 2,477,383 (the alkyl radical can be a straight or branched aliphatic chain); sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of sulfuric acid esters of the reaction product of one mole of a higher fatty alcohol (e.g., tallow or coconut oil alcohols) and about 1 to 6 moles of ethylene oxide; sodium or potassium salts of alkyl phenol ethylene oxide ether sulfate with about 1 to about 10 units of ethylene oxide per molecule and in which the alkyl radicals contain from 8 to about 12 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil; sodium or potassium salts of fatty acid amide of a methyl tauride in which the fatty acids, for example, are derived from coconut oil; and others known in the art, a number being specifically set forth in United States Letters Patent Numbers 2,486,921; 2,486,922 and 2,396,- 278. Another important anionic detergent is described, by way of example only, as comprising by weight from about 30% to about 70% of Component A, from about to about 70% of Component B, and from about 2% to about 15% of Component C, wherein:

said Component A is a quaternary mixture of double bond positional isomers of water-soluble salts of alkenel-sulfonic acids containing from about 10 to about 24 carbon atoms, said mixture of positional isomers including by weight about 10% to about 25% of an alphabeta unsaturated isomer, about to about 70% of a beta-gamma unsaturated isomer, about 5% to about 25% of a gamma-delta unsaturated isomer, and about 5% to about 10% of a delta-epsilon unsaturated isomer;

said Component B is a mixture of water-soluble salts of bifunctionally-substituted sulfur-containing saturated aliphatic compounds containing from about 10 to about 24 carbon atoms, the functional units being hydroxy and sulfonate radicals'with the sulfonate radical always being on the terminal carbon and the hydroxyl radical being attached to a carbon atom at least two carbon atoms removed from the terminal carbon atoms; and

said Component C is a mixture comprising from about 3095% water-soluble salts of alkene disulfonates containing from about 10 to about 24 carbon atoms, and from about 5% to about 70% Water-soluble salts of hydroxy disulfonates containing from about 10 to about 24 carbon atoms, said alkene disulfonates containing a sulfonate group attached to a terminal carbon atom and a second sulfonate group attached to an internal carbon atom not more than about six carbon atoms removed from said terminal carbon atom, the alkene double bond being distributed between the terminal carbon atoms and about the seventh carbon atom, said hydroxy disulfonates being saturated aliphatic comcompounds having a sulfonateradical attached to a terminal carbon, a second sulfonate group attached to an internal carbon atom not more than about six carbon atoms removed from said terminal carbon atom, and a hydroxy group attached to a carbon atom which is not more than about four carbon atoms removed from the site of attachment of said second sulfonate group.

(b) Nonionic synthetic detergents of the following types may be used in the process of this invention in addition to the alkylene oxide-containing nonionic synthetic detergents hereinbefore described:

(1) Long chain tertiary amine oxides corresponding to the following general formula, R R R N 0, wherein R is an alkyl radical of from about 8 to about 18 carbon atoms, and R and R are each methyl or ethyl radicals. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of amine oxides suitable for use in this invention include dimethyldodecyl amine oxide, dimethyloctylamine oxide, dimethyldecylamine oxide, dimethyltetradecylamine oxide, dimethylhexadecyl amine oxide.

(2) Long chain tertiary phosphine oxides corresponding to the following general formula RR'RP O wherein R is an alkyl, alkenyl, or monohydroxyalkyl radical ranging from 10 to 18 carbon atoms in chain length and R and R" are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbon atoms. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of suitable phosphine oxides are: dodecyldimethylphosphine oxide, tetradecyldimethylphosphine oxide, tetradecylmethylethylphosphine oxide, cetyldimethyl phosphine oxide, stearyldimethylphosphine oxide, cetylethylpropylphosphine oxide, dodecyldiethylphosphine oxide, tetradecyldiethylphosphine oxide, dodecyldipropylphosphine oxide, dodecyldi (hydroxmethyl) phosphine oxide, dodecyldi (Z-hydroxyethyl) phosphine oxide, tetradecylmethyl 2 hydroxypropyl phosphine oxide, oleyldimethylphosphine oxide, and 2 hydroxydodecylme'thylphosphine oxide.

(0) Arnpholtic synthetic detergents can be broadly described as derivatives of aliphatic secondary and tertiary amines, 'm which the aliphatic radical may be straight chain or branch and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfo, sulfato, phosphato, or phosphono. Examples of compounds falling Within this definition are sodium-3- dodecylaminopropionate and sodium-3-dodecylaminopropane sulfonate.

(d) Zwitterionic synthetic detergents can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radical may be straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic Water solubiliaing group, e.g., cat-boxy, sulfo, sulfato, phosphato, or phosphono. Examples of compounds falling within this definition are 3-(N,N-dimethyl-N-hexadecylammonio) propane-l-sulfonate and 3-(N,N-dimethyl-N- dodecylammonio)-2-hydroxy propane-l-sulfonate which are especially preferred for their excellent cool water detergency characteristics.

The soap and non-soap anionic, nonionic, ampholytic and zwitterionic detergent surfactants mentioned above can be used singly or in combination in the practice of the present invention. The above examples are merely specific illustrations of the numerous detergents which can find application within the scope of this invention. Other surfactants Within the prescribed classes can also be used.

It will be understood by the worker skilled in the art that detergent slurries of this invention, and the detergent compositions made therefrom, will ordinarily contain various other ingredients for special purposes. Thus, the detergent slurries of this invention can contain suds builders, bleaches, suds depressants, anti-corrosion agents, re-

deposition agents, dyes, fiuorescers, perfumes, sodium sulfates, sodium carbonates and the like. Again, the use of any such detergent ingredients forms no limitation on the invention but is intended merely to be includable within the terms of claims calling for a detergent slurry comprising various detergent ingredients.

A highly desirable, controlled sudsing, laundry detergent product can be obtained by incorporating from about 1% to about 15% of an anionic synthetic detergent, as hereinbefore described, into the detergent slurry of this invention. As a more preferred embodiment, the anionic synthetic detergent should be added in a weight ratio to the hereinbefore described essential nonionic synthetic detergent of from 3:1 to 1:6.

The following examples merely serve to illustrate the invention in specific detail, and when read in conjunction with the foregoing description will aid in determining the full scope of the present invention. The examples are merely illustrative and they are not in any Way intended to restrict the invention.

EXAMPLE I Detergent slurries having the compositions shown in Table 1 were prepared in a SOO-gram, stainless steel crutcher. This crutcher was surrouned by a jacketed space through which water at about 135 F. flowed continuously. The crutcher was equipped with a propeller-type mixer and a thermometer. The various detergent ingredients were added to the crutcher in the order shown by Table 1.

TABLE 1.COMPOSITIONS OF DETERGENT SLURRIES Runs 81 Detergent Ingredients (gms):

Linear sodium alkyl benzene sulfonate paste (hereinafter referred to as LAS paste) (alkyl moieties range from 10 to 18 carbon atoms;

the paste is comprised of 53% water, 21%

sodium sulfate, 26% linear alkyl benzene sulfonate) .1 252 1 252 2 126 1 126 Z 227 2 227 Condensation reaction product of one mole of tallow alcohol and 10 moles of ethylene oxide (TE o) 3 31. 5 3 31. 5 3 6. 3 3 6.3 1 63 7 63 7 63 Sodium Sulfate b .c .c 4 4 35 4 14 4 14 3 3 60 1 60 Sodium silicate (SiOz. azO= 6.1) (0.435

solids) 3 47 5 47 5 47 5 47 5 47 4 46 4 46 4 46 Trisodium nitrilotriaeetate monohydrate (Na NTA) 4 38 6 38 6 38 5 38 5 188 Anhydrous tripolyphosphate (STP) 4 175 5 140 B 175 7 140 6 175 7 140 5 175 140 \Vater I. 1 1 67 1 14 1 l1 2 139 1 136 1 126 Weight Ratio STP:Na NTA 4:1 1. 4:1 4:1 4:1

Approx. Slurr; Temp. F.)- 138 138 135 135 129 136 138 140 0 Slurry after addition of TE. Grainy Grainy Grainy Grainy \ffery Grainy Grainy iscous Slurry after addition of STP Smooth Smooth Unpump- Smooth Unpump- Smooth Two Smooth Smooth able able Phases *Superscripts indicate order of addition.

a The Slun'ies from Runs 1, 2, 4, 6, 8 and 9 were spray dried. The yield from each of these runs was about 350 grams. b Sodium sulfate added in addition to that amount present in the LAS paste.

In Runs 1 and 2, wherein no nonionic was included in the slurry, no emulsion problems were presented. The slurry was smooth, homogeneous and pumpable from the addition of the LAS paste until the final addition of the STP.

In all the remaining runs, TE was added to the slurry before Na NTA. The slurry, in all cases, became grainy and a perceptible increase in viscosity was noted. The slurry was, however, still pumpable.

When no Na NTA was added to the slurry, as shown by Runs 3, 5, and 7, the slurry became highly viscous and unpumpable With ordinary equipment useful in spray dryin In Runs 3 and 5 the slurry became so viscous that the propeller mixer was stopped. In these runs, only about three-fourths of the amount of STP indicated in Table 1 could be incorporated into the detergent slurry.

EXAMPLE H Detergent slurries having the compositions shown in Table 2 were prepared in the crutcher described in Example I. Water flowing through the jacket was maintained at a temperature of 135 F. In all cases, except Runs 9 and 10, the slurries described in Table 2 were spray dried. The resultant product from each spray dried run weighed about 350 grams.

TABLE 2.COMPOSITION OF DETERGENT SLURRIES Runs Deterges? .1 1 126 1 126 1 I26 1 126 2 126 2 3 5 3 563 63 31.5 31.5 31.5 31.5 63 31.5 42 42 42 42 42 42 42 342 442 379 5 279,5 279,5 79.5 79.5 79.5 79.5 79.5 79.5 79.5 5 90. 5 4 90. 5 4 144 5 181 181 5 181 5 90. 5 11 90. 5 6 90. 5 7 90. 5 6815 0315 635 87.5 87-5 87.5 87.5 1 123 1 123 1 122 1 1 25 2 25 2 28 2 28 1 123 1 28 1:1 1:1 1:4 111 1:1 1:1 1:1 132 132 132 128 128 134 136 137 Superscripts indicate order of addition.

Before the addition of Na NTA in Run 1, the slurry had separated into two distinct phases. The nonionic was floating on the surface; the water, sodium sulfate and sodium silicate formed a curdy, grainy layer beneath the nonionic. With the addition of Na NTA to the slurry, the two phases were elminated, viscosity was decreased and the curds were broken up and dispersed..Addition of STP to the slurry resulted in only a very slight viscosity increase. The final detergent slurry was smooth, homogeneous and easily pumpable.

Run 2 contained exactly the same detergent ingredients as Run 1. However, Na NTA was added to the slurry TABLE 3.COMPOSITION 1 2 EXAMPLE 1n Detergent slurries having the compositions shown in Table 3 were prepared in the crutcher described in Example I. Water flowing through the jacket was maintained at a temperature of 135 F. In all cases, the slurries described in Table 3 were spray dried. The resultant product from each run weighed about 350 grams.

DETERGENT SLURRIES Runs eter ent In edients ms. D LES Pa e ...2 126 126 126 126 126 31% 31% 63 31% 31% 31% 42 42 42 42 42 79% 79% 79% 79% 79% 79% 45 54 37 45 54 37 133 123 140 133 123 140 Water 123 123 124 124 126 29 29 28 29 29 Weight Ratio STP:Na NTA :25 30:20 :15 :10 37%:12% 35:15 40:10 37%:12% 35:15 40:10 Approximate Slurry Temperature, F 134 135 136 124 134 3 130 128 132 136 In Run 4 when the nonionic was added to the slurry, the slurry separated into two grainy layers. Again the nonionic was floating on the top of the second layer. On addition of Na NTA, the layering etfect disappeared and the final slurry was smooth and homogeneous.

As the nonionic was added to the slurry in Run 5, the slurry became very viscous. As mixing was continued, the viscosity increased until finally the propeller mixer would not turn. Na NTA was forced into the jelly-like slurry by hand. The slurry gradually regained its former relatively low viscosity and was pourable and pumpable.

The slurries prepared in Runs 6 and 7 were smooth, homogeneous and easily pumpable from start to finish. No problems were encountered in preparing the slurry.

In Run 8, the addition of TE caused the slurry to become quite viscous and barely purnpable. Upon the addition of Na NTA, the slurry became fluid and homogeneous. STP was added with only a very slight increase in viscosity. The final slurry was smooth, homogeneous and pumpable.

In Run 9, the addition of the nonionic caused the slurry to become grainy and to separate into two phases. The addition of STP caused a sharp increase in viscosity. The slurry would not flow from the crutcher when it was inverted. The subsequent addition of NagNTA did not effect the viscosity of the slurry. The result was very viscous, unpnmpable, grainy, heterogeneous detergent mass which was not suitable for use in any ordinary detergentmaking process.

In Run 10, the addition of the STP caused the slurry to become grainy, clabber-like and very viscous. In attempting to incorporate TE into the detergent mass, the high viscosity of the slurry stopped the mixer. Na NTA could not be homogeneously admixed therein. The resultant detergent mass was unpnmpable and heterogeneous.

Froma comparison of Runs 1 through 8 it will be observed that it is significantly more advantageous to add the Na NTA to the detergent slurry before the addition thereto of an alkylene oxide-containing nonionic synthetic detergent. The Na NTA prevents the intermediate elfects of layering, viscosity increases and grainy slurries. The end products, however, are very similar.

Runs 9 and 10, in conjunction with Runs 1 through 8, indicate that the hydratable builder 'salt should be added after both the nonionic and NTA have been homo- V geneously admixed in the slurry to prevent the formation of heterogeneous, unpumpable detergent slurries.

In all runs in this example, the essential ingredients were added to the slurry in the following order: Na NTA, nonionic, and finally STP. In all cases, the slurries were smooth and homogeneous. All of these slurries were pumpable and can be used satisfactorily in a spray drying operation. Even Runs 4, 7 and 10, which formed fairly viscous slurries can still be used. A less viscous slurry than those in Runs 4, 7 and 10, however, is more desirable. Runs 5 and 8 were, likewise, quite viscous. A significant factor here was that as the ratio of STPzNa NTA decreased, the slurry became less and less viscous;

Pumpable as used herein in characterizing a detergent slurry refers to the consistency or viscosity of that slurry. A desired synthetic detergent slurry at from about 30% to about 38% moisture at a temperature of about F. has a viscosity of about 10,000 centipoises. This slurry is pumpable and excellent for use in ordinary spray drying equipment. Pumpable, as used herein, defines the viscosity of a detergent slurry which is suitable for use in such ordinary spray drying equipment. In no case should the viscosity of this final slurry exceed 50,000 centipoises. Viscosities less than about 5,000 centipoises are not common.

EXAMPLE IV Detergent slurries having the synthetic detergent compositions shown in Table 4 when prepared according to the procedure described below remain pumpable, smooth and homogeneous through all processing steps. The composition of the final detergent slurry and the order of addition of the ingredients in each of the runs are as follows:

Grams l. Anionic Paste 126 2. Water 28 3. Sodium Sulfate 42 4. Sodium Silicate 79.5 5. Nonionic 31.5 6. Na NTA* 90.5 7. STP 87.5

See Example I for more complete definition.

TABLE 4.SYNTHETIC DETERGENT COMPOSITOIN OF DETERGENT SLURRIES Detergent Ingredients (gms.)

Runs

Anionic Paste (53% Water, 21% sodium sulfate, 26% active as listed below):

Sodium tallow alcohol sulfate Sosium alkyl benzene sulionate (alkyl chain contains from 9-15 carbon atoms)- Sodium tallow glyceryl ether su1ionate Olefin Sulionate Sodium alkyl phenol ethylene oxide ether sulfate containing 8 units of ethylene oxide per molecule Nonyl phenol containing 30 units of ethylene oxide per molecule Dodecyl mereaptan containing 10 units of ethylene oxide per molecule Dinonylphenol containing units of ethylene oxide per molecule Plurorn'c L64 (as described above) TEm (See Exampie I) I claim: 1. The process of preparing a homogeneous detergent slurry comprising the steps of (a) mixing, by Weight of the final detergent slurry, from about 25% to about 40% water, from about 1% to about of an alkylene oxide-containing nonionic synthetic detergent, from about 1% to about 50% of the trisodium salt of nitrilotriacetic acid, said salt of nitrilotriacetic acid being added in amount sufiicient to provide an easily pumpable, homogeneous slurry but in an amount less than its own solubility in the final slurry; and thereafter,

(b) adding and mixing homogeneously therein to form the final slurry from about 5% to about 60% of an hydratable sodium tripolyphosphate builder salt; the amount of said builder salt being not more than about five times the weight of said trisodium salt of nitrilotriacetic acid.

2. The process of preparing a homogeneous detergent slurry suitable for spray drying comprising the steps of:

(a) mixing by weight of the final detergent slurry, from about to about 40% water and from about 1% to about 50% of the trisodi-um salt of nitrilotriacetic acid, said salt of nitrilotriacetic acid being added in amount sufl'icient to insure the formation of an easily pumpable, homogeneous slurry but in an amount less than its own solubility in the final slurry;

(b) adding and mixing homogeneously therein, from about 1% to about 20% of an alkylene oxide-containing non-ionic synthetic detergent; and thereafter (c) adding and mixing homogeneously therein to form the final slurry, from about 5% to about 60% of hydratablc sodium tripolyphosphate builder salts;

the amount of said builder salts being not more than about five times the weight of said trisodium salt of nitrilotriacetic acid, while ((1) maintaining the temperature of said slurry throughout its preparation at from about F. to about 200 F.

3. The process of claim 1 wherein the detergent slurry comprises from about 30% to about 38% water by weight of the final detergent slurry.

4. The process of claim 1 wherein the detergent slurry comprises from about 2% to about 30% of the trisodium salt of ntrilotriacetic acid by Weight of the final detergent slurry.

5. The process of claim 1 wherein the detergent slurry comprises from about 2% to about 15% alkylene oxidecontaining nonionic synthetic detergent by Weight of the final detergent slurry.

6. The process of claim 1 wherein the temperature of the slurry throughout its preparation is maintained at a temperature of between F. and 160 F.

7. The process of claim 1 wherein the detergent slurry contains from about 1% to about 15% of an anionic non-soap synthetic detergent.

References Cited UNITED STATES PATENTS 2,921,908 1/1960 McCune 2521 10 3,067,144 12/1960 Michaels 252-437 3,122,508 2/1964 Grifo 252 3,303,134 2/1967 Sheu 252135 LEON D. ROSDOL, Primary Examiner. S. E. DARDEN, Assistant Examiner. 

1. THE PROCESS OF PREPARING A HOMOGENEOUS DETERGENT SLURRY COMPRISING THE STEPS OF (A) MIXING, BY WEIGHT OF THE FINAL DETERGENT SLURRY, FROM ABOUT 25% TO ABOUT 40% WATER, FROM ABOUT 1% TO ABOUT 20% OF AN ALKYLENE OXIDE-CONTAINING NONIONIC SYTHETIC DETERGENT, FROM ABOUT 1% TO ABOUT 50% OF THE TRISODIUM ALT OF NITRILOTRIACETIC ACID, SAID SALT OF NITRILOTRIACETIC ACID BEING ADDED IN AMOUNT SUFFICIENT TO PROVIDE AN EASILY PUPABLE, HOMOGENEOUS SLURRY BUT IN AN AMOUNT LESS THAN ITS OWN SOLUBILITY IN THE FINAL SLURRY; AND THEREAFTER, (B) ADDING AND MIXING HOMOGENEOUSLY THEREIN TO FORM THE FINAL SLURRY FROM ABOUT 5% TO ABOUT 60% OF AN HYDRATABLE SODIUM TRIPOLYPHOSPHATE BUILDER SALT; THE AMOUNT OF SAID BUILDER SALT BEING NOT MORE THAN ABOUT FIVE TIMES THE WEIGHT OF SAID TRISODIUM SALT OF NITRILOTRIACETIC ACID. 